The present invention relates generally to switched telephone networks for serving an area which is divided into relatively small service zones in which cordless telephones are located, and more specifically to a channel assignment technique for use with such cordless telephone networks.
With cellular mobile telephony, automobile stations are usually located at such greater distances apart that signals transmitted from mobile stations are not strong enough to interfere with other stations to produce intermodulation products, No difficulty arises in assigning speech channels to the mobile stations. However, with microcellular systems which are currently employed in business environments, the service area is divided into small zones, or microcells with a radius of as small as several tens of meters and cordless telephones are usually located at short distances apart. In some instances, the distance between adjacent cordless stations may be as short as 1 meter. In addition, the size and shape of each of the microcells differ from one cell to another and a great number of base units must be provided. One problem associated with such microcellular systems is that due to the high density of cordless units intermodulation products are often generated between adjacent units and seriously affect the operation of the system.